Impact of DC-DC converter interconnections on the performance of bidirectional EV chargers

The shift towards electric vehicle (EV) adoption requires a solid and efficient charging infrastructure. A crucial part of these systems is the DC-DC converter, which connects the power grid or energy storage with the vehicle's battery pack. Conventional single-module DC-DC converters have inherent limitations in addressing the rising demands for higher power levels, enhanced efficiency, and greater operational reliability in current EV charging applications. The interconnection of several DC-DC converter modules is a promising method to overcome these obstacles, enabling increased power output and better fault tolerance. This research explores the performance of a dual-stage bidirectional EV charger featuring different interconnections. A comprehensive small signal averaged model of the DC stage of the dual-stage EV charger is presented for both the single converter and two converters connected in an interleaved configuration, including a stability analysis. Further, a relative assessment of the charger's performance with the various interconnections is performed, and the results are detailed in terms of various performance metrics, including efficiency, ripple percentage, and source power factor. The conclusions obtained from the comparative analysis are explicitly illustrated to facilitate the selection of the appropriate interconnection for a given application.